There are times when I wish I had had debate training at school or university, but Tuesday 29 November wasn't one of them. Six of us were divided into two competing teams, with a chairman to prise us apart when we went for the kill. The subject: Christmas dinner in the year 2050. The idea: to use the yuletide menu as a lens through which to view the future. The venue was the British Medical Association, so doctors were nearby had the infighting become bloody. But as it went, I was told later, you could scarcely see the wounds as the sniping began and the bodies slid to the floor.

There were two scenarios, each championed by a team of three led by a senior executive from Atkins, one of the world's leading engineering and design consultancies. The first was "laissez-faire", in which the market ruled and no holds were barred. The second, and this is the one I was asked to support, was "less is more", envisioning a world where climate and other drivers had forced a more considered, managed and planned approach to the future. Despite the turmoil in global markets, when the first round of electronic voting was run with the audience of 100-plus people, laissez-faire led by a considerable margin.

Naturally, as is the way with such debates, our opponents pitched their future as irresistibly glorious, in the circumstances. Yes, Christmas temperatures would be significantly higher than we are used to today, and UK temperatures would regularly be reaching a sweltering 40°C during the summer months. But the fictional Smith family, who we had been asked to focus on, were making the best of things – with a wall-to-wall solar array on the roof, a windmill in the garden and an array of homegrown or locally produced tropical products on the menu.

Market rules may not be perfect, but overall, we were assured, over time, via Adam Smith's invisible hand, they would be delivering cost-effective solutions. On the upside, in this future vision gardens routinely sport coconut palms. A more complicated idea was that because rainfall patterns will have shifted in such a way that Scotland becomes a world leader in rainfall, much of the fresh water a water-starved London will need is pumped south in massive pipelines. Water, it seems, now rivals oil as a leading Scottish export. In a linked and surprising development, much of the London tube system has been turned into a vast underground reservoir.

And then the laissez-faire team went for a full-frontal assault on the planned economy. This would automatically lead to tyranny, they insisted, with the outcome a bit like the European commission – which has only ever brought us bendy busses and bendy bananas – on speed.

We begged to disagree, noting that many of the improvements in the future envisioned by our rivals (as they rashly admitted), depended on climate policies and carbon pricing introduced by people the leader of the opposing team described as "those clever folks at the ministry".

We also pointed out that a two-degree rise in average temperatures did not simply mean that it would be possible to sit out in deckchairs for a few weeks longer each year. Instead, it potentially would mean massive disruptions to our agricultural and water supply systems, quite apart from the threat of environmental refugees swarming out of North Africa into Europe.

I further rattled the bars by suggesting that we were wrong to follow the brief and focus on the Smiths when it made more sense, given the global implications of climate change, to think about the Patels, the Wus, the Okonkwos and the Popovs. I wondered, too, what the water extracted from the tube system would actually taste like?

Because the event was subject to the Chatham House Rule, I can't attribute quotes, except perhaps to myself. When the rival team concluded with a celebration of the role of new technology, I found myself channeling Tom Midgley – someone who, it turned out, was unknown to the audience.

I recalled that in the 1920s and 1930s Midgley came up with several technologies that were seen as health or environmental godsends at the time. One was leaded petrol, a big step forward for fuel efficiency at the time, but where the lead in car exhaust emissions ended up poisoning children. Another of his insanely clever inventions: chlorofluorocarbons, a semi-miraculous improvement on previous aerosol propellants, which had proved deadly when inhaled by young people, for whatever purpose. But, once used at scale, CFCs went on – in a classic case of capitalism's invisible elbow – to blow a continent-sized hole in the planet's stratospheric ozone layer.

Laissez-faire, in a world rocketing towards nine billion people, would likely be a jarringly rough ride. Instead of the traditional Christmas fare, we could well end up eating the roast jellyfish someone had jokingly proposed as a key menu item for 2050. Surprisingly, my suggestion that environmental and resource pressures would mean that everything on the menu would be genetically engineered triggered no pushback.

Finally, I noted that history suggests laissez-faire politics will likely drive us even closer to the socially skewed world of Charles Dickens. (A blue plaque outside the BMA's headquarters, where the event was heldsaid the author had lived in a house on the same spot.) Yes, a wealthy family's Dickensian Christmas might have featured a groaning table and flushed faces inside, but outside the pinched noses of the poor would have been pressed in quiet desperation to the frosted windows. Quiet desperation is unlikely to be the response in such a divided future.

Which brings us to the final vote. Despite having broken many of the rules of polite debate, and soft-heart that I am, I found myself feeling quite distressed for our opponents. We won by a window-rattling landslide. The winning team received bottles of an excellent English champagne (thank you global warming), while the losers received a do-it-yourself Christmas pudding kit. At least it wasn't a ready-roast jellyfish, though they're something else that climate change is now driving in the direction of our shores and, just maybe, our dinner tables.